Multiple glazing, method for obtaining same and device for using said method

ABSTRACT

The invention relates to multiple glazing, a method of obtaining the same and a device for using said method. The glazing contains two sheets of glass separated by a space of dehydrated air and maintained by a cross-braced frame, of which at least the surface in contact with the glass is butyl and/or polyisobutylene rubber-based mastic and is covered with a peripheral injection, which adheres in a cohesive maner to the mastic of the cross-braced frame.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to multiple glazings formed from at leasttwo sheets of glass separated by a gas space, generally air, providingheat insulation. The invention also relates to a technique for obtainingsuch multiple glazings.

2. Discussion of the Background

Double glazing, or more generally multiple glazing, is graduallyequipping the majority of recently constructed or older dwellings due tothe improvement in heat and/or acoustical comfort and the energy savingswhich it provides.

Diffusion of double glazing, however, runs into a two-fold problem:

(a) first, it is still frequently a craftsman-like product with multiplemanufacturing steps and is, therefore, relatively expensive,

(b) second, this type of glazing is difficult to adapt to old frameswhose grooves only allow the introduction of a single sheet of glass.

Present double glazing is basically of two types which can bedifferentiated by the type of interposed cross-braced frame whichmaintains the sheets of glass apart.

In accordance with a first type, the cross-braced frame is composed ofrigid metal profiles joined together, which are, for example, aluminum.In this case, the frame does not adhere to the sheets of glass and doesnot act as a seal, which is provided by the in situ injection of aperipheral polymerizing joint, for example polysulfide.

An improvement in this type of glazing with a rigid cross-braced frameis obtained if an organic joint is interposed between the frame and theglass, for example a polyisobutylene and/or butyl rubber-based joint,which essentially guarantees a seal against water vapor, with a secondjoint, for example in polysulfide which is more water-impermeable,reinforcing the seal. This type of double glazing, which for example issold by Applicant under the trademark Polyglass®, performs very wellbecause it is remarkably water-tight but is relatively expensive.

For its manufacture, a frame with the dimensions of the glazing must beproduced by fitting profiles together, filling the profiles with adrying agent, such as a molecular sieve, coating their two oppositeexternal surfaces with a polyisobutylene and/or butyl rubber-basedmastic, placing the frame prepared in this manner between two sheets ofglass, injecting a peripheral joint, for example of polysulfide into thegroove defined by the edges of the two sheets of glass on each side ofthe profile and polymerizing the polysulfide.

A second type of double glazing is composed by glazing not having arigid cross-braced frame, but two peripheral joints, that is, aninterior butyl rubber-cased cord which also acts as a separator for thesheets of glass and an exterior polysulfide joint. This type of glazing,sold by Applicant under the trademark Biver® and described, inparticular, in French Pat. Nos. 2,294,313 and 2,294,140, enablesautomated industrial manufacture by replacing the manual operation offitting together the profiles with automated in situ extrusion of acord.

In addition, the butyl rubber-based cord, which is also called the butylcord, adheres to the glass and forms a first sealing barrier. Therefore,as in the case of Polyglass®, this guarantees a longer life for theglazing which is exposed on the one hand to the infiltration of rainwater, in the case of a damp atmosphere, particularly when used forkitchens, bathrooms, etc., and to variations in climate, which,depending on the outside temperature, cause the interposed sheet of gasto dilate or to contract, thus producing breathing of the glazing whichbasically makes it fragile at the sealing joints.

This breathing of the multiple glazing constitutes a general problem forall multiple glazing and requires great precautions at the time oflaying the peripheral joints so as to prevent leaks at the glass-jointinterface, particularly in the angles. Care should also be taken toensure that air bubbles are not imprisoned at the interface of thejoints, bubbles which by expanding and contracting in turn could lead toa loss in sealing.

These manufacturing defects, the practical consequences of which onlyoccur a few years after the final placing of the glazing can only beovercome by using very qualified personnel and staff responsible forchecking the quality of the work after the manufacturing step; in otherwords, using an expensive infrastructure.

SUMMARY OF THE INVENTION

The principal object of the present invention is to provide a new typeof multiple glazing which is certain to provide perfect sealing withoutincreased checking being necessary.

A further object of the invention is to provide a method of maufacturingthe new type of multiple glazing which assures quality manufacturing yetreduces costs.

Another object of the invention is to provide a device with which tocarry out the method of the present invention which is economical andyet versatile enough to produce several embodiments of the multipleglazing of the present invention.

These objects and other objects of the present invention have beenachieved by the present multiple glazing, comprising:

two or more sheets of glass separated by an interposed gas space,wherein said glass sheets are maintained mutually substantially parallelby means of a cross-braced frame and a peripheral joint, saidcross-brace frame comprising butyl rubber or polyiosbutylene-basedmastic at the contact surface between said glass sheets and saidcross-braced frame, and wherein said peripheral joint comprises aplastic capable of adhering in a cohesive manner with said butyl rubberof said polyisobutylene-based mastic,

and by the method of producing said multiple glazing and the device forperforming said method disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 illustrates a vertical cross-section of different types ofmultiple glazing in accordance with the invention (FIGS. 1a, 1b, 1c).

FIG. 2 shows a diagram viewed from above of a mold enabling theproduction of glazing as in FIG. 1,

FIG. 3 illustrates a vertical cross-section along plane A--A of FIG. 2,

FIG. 4 illustrates a vertical cross-section of a mold in accordance withthe invention, more particularly adapted to injection under lowpressure,

FIG. 5 shows a diagram of a material circuit for the liquid compounds,and

FIG. 6 shows a diagram of a static mixer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The multiple glazing in accordance with the invention contains aperfectly continuous double sealing barrier, with the second sealingjoint adhering in a cohesive to the first of the sealing joints.

By butyl rubber and/or polyisobutylene based mastic is meant a masticwhich remains permanently malleable, as is described in French Pat. No.2,294,313. Such a mastic can perfectly assure the separation of twoglass sheets during the period of a few hours, which is much more thanthe time necessary to completely make the multiple glazing. However, itcannot be used as a spacer during the whole life of the glass product,that is, 10 years minimum. The exterior peripheral joint serves equally,therefore, as a spacer, since in collaboration with the cross-bracedframe, it must fit in the area between the sheets of glass in the onehand, and as the cross-braced frame on the other hand.

In accordance with the invention, the exterior peripheral joint is suchthat it adheres in a cohesive manner onto the interior joint, or theorganic part of said interior joint, which, for example, ispolyisobutylene and/or butyl rubber-based. "Adheres in a cohesivemanner" is used to mean the production of bonds such that the separationof the two materials is impossible, unless one of them is destroyed. Theproblem of the interface between the two joints is therefore solved byan interpenetration of the materials at the interface, without however,removing the principle of a double sealing barrier.

This can be obtained by using as an exterior peripheral joint, the insitu condensation product of a reactive mixture composed of at least tworeagents in the liquid state, whose fluidity is close to that of waterunder normal conditions of temperature and pressure. The peripheraljoint is thus a liquid, fixed by the polymerization reaction but which,before this reaction takes place, can occupy the smallest spaces.

The injection pressure of the reactive mixture is sufficient for no airbubbles to be imprisoned at the interface between the joints. Such wasnot the case with the sealing mastics of the prior art, such aspolysulfides or silicon elastomers, whose viscosity at the moment oftheir injection through a nozzle turning around the glazing is fairlycomparable to that of molasses. These mastics required very elaboratemethods of use.

The condensation product is preferably a polyurethane produced from thereaction of a polyisocyanate and a polyol. Preferably, an aliphaticpolyisocyanate is used, which practically eliminates any ultra-violetsensitivity of the polyurethane.

The polyurethane must have an instanteous Shore hardness of between 50and 70 Shore A, stretching to rupture of 400% at 20° C. and lowpermanent deformation on compression.

Preferably the reactive mixture is such that the condensation reactiontakes place in an optimum time at a temperature of between 40° and 70°C.

In accordance with a further particularly preferred characteristic ofthe invention, the external peripheral joint fills not only the groovedefined by the two sheets of glass on the one hand and the internaljoint on the other hand, but also covers the peripheral part of theexternal surfaces of the glass, thus masking all or part of the joints.

This arrangement is particularly preferred for the many advantages whichare obtained. First, it improves the water-tightness at the joint-glassinterface, which is systematically the weak point of any multipleglazing. It should first be noted that, since in accordance with theinvention it is obtained by in situ condensation of a liquid mixture,the polyurethane joint closely follows the contours of the glass andthere is, therefore, a suction effect which contributes to the sealingof the joint-glass interface. In addition, as soon as the polyurethanejoint is placed on either side of the sheets of glass, the path whichwater must follow before reaching the second joint, which it must thenstill traverse, is thus greatly lengthened, such that the probability ofinfiltration is further decreased. In addition, the problem posed by thesuccessive contractions and expansions of the sheet of interposed gas,which has already been mentioned, causes "breathing" of the glazing. If,as in accordance with the preferred characteristic which is developedherein, the polyurethane joint is placed covering the glazing, thebreathing phenomenon is selfcompensated.

In effect, in the case of contraction of the glazing, the part of theperipheral joint which is inside the multiple glazing is placed in acompressed state and strongly repels infiltrations. On the other hand,in the case of expansion, the sheets of glass tend to separate mutuallyand, in this case, the part of the peripheral joint which is outside theglazing prevents this movement. In all cases, part of the joint has anincreased barrier role.

To this sealing aspect, an aspect of protection for the glazing isadded, more particularly for the edges, especially for the possibilityof stacking the glazing one on top of the other without having tointerpose wedges between them, since the glazed surfaces are not incontact with one another due to the overthickness of the joint and alsoare less fragile. This greatly facilitates all the operations of on-sitehandling and laying.

Finally, there is an esthetic aspect, with the exterior part of thepolyurethane joint masking its own interior part and the first internaljoint and capable of being either tinted or painted to match the frames.

The invention also provides a method for manufacturing double glazingwith a continuous double barrier. This method is characterized in that,in a first step, a temporary double glazing is produced in a knownmanner, the double glazing formed by two parallel sheets of glassmaintained in separation by a crossbraced frame, of which at least thesurface in contact with the sheets of glass is butyl rubber and/orpolyisobutylene-based and in that, in a second step, a heated mold isplaced around the area of the edges of the temporary glazing thusdefining over the entire periphery of the glazing a cavity which is thenrendered sealed by exerting traction on each sheet of glass and intowhich the reactive mixture is injected.

This method of placing the exterior peripheral joint comprises twoessential characteristics:

(1) the so-called reactive injection mold and,

(2) the glazing is maintained under traction throughout the moldingoperation.

Reactive injection molding signifies that the reactive mixture isintroduced in the liquid state and, due to its fluidity, occupies allthe available space, all the empty spaces, and exactly follows thecontours of the glass and in particular of the cross-braced frame whilepreventing the imprisonment of air bubbles at the interface of the twojoints.

A further advantage of the reactive injection molding method is that itenables handling of the glazing upon release from the mold without fearof them sticking together or becoming scratched. In other words, theglazing is immediately usable, whereas for the preparation of a doubleglazing comprising a peripheral polysulfide or silicon joint, the jointmust first be injected with a nozzle turning for example around theglazing, then the joint must be polymerized for a time which is neverless than one and one-half hours and often on the order of 12 or even 24hours, either in a an oven or in a chamber at room temperature where theglazing must be taken using great precautions. Further, the joint beforepolymerization has the consistency of molasses as has already beenindicated.

The second characteristic of the method in accordance with the inventionis that the glazing is placed in a state of traction during the moldingof the peripheral joint, which ensures that the glazing presses againstthe mold. Preferably, this traction is exerted by vacuum suction, butother means, in particular mechanical means, are also capable of beingused.

This characteristic can be used because Applicant has notedexperimentally that, in a surprising manner, the butyl rubber and/orpolyisobutylene-based joints do not then react by becoming detached fromthe glass but by becoming thinner in their central part. The sealcreated between the mold and the glass does not therefore create a leakat the cross-braced frame.

The method in accordance with the invention enables this property of thebutyl rubber and/or polyisobutylene-based joints to be used toadvantage. Thus, by vacuum drawing it is possible to extend thethickness of the cord by close to 20%. This extension may, if necessary,go up to close to 25% by using auxiliary mechanical drawing means suchas suction cups placed on the two opposite surfaces of the doubleglazing. This can be very useful for the manufacture of multiple glazingin which the interposed air space has a thickness of more than 20 mm,for example. Glazing of this type would otherwise require greatprecautions to be taken when laying the butyl rubber cord.

On the other hand, the closing of the mold can be used to reduce thethickness of the interior cord by compression and can preferably besubstituted for the operation of pressing the sheets of glass.

The method in accordance with the invention enables an interior cord tobe obtained which is perfectly sized just as the exterior templateconforms perfectly three-dimensionally to the desired template.

The injection of the reactive mixture can, depending on its reactivity,be carried out at high or low pressure. At high pressure, which isapproximately 200 bars, the time for injection and setting are extremelyshort, preferably less than 1.5 seconds, which enables very high ratesof production. The products used for the method are selected for examplefrom among those proposed for the encapuslation of automobile glassesusing the RIM (reactive injection molding) process, for which the threadtime is on the order of 2 seconds.

The injection can also be carried out at low pressure. Low pressure heremeans a pressure below 100 bars, preferably between 3 and 7 bars, for aninjection time of more than 60 seconds, used with reactive mixtureswhose thread time is a few minutes and preferably on the order of 90seconds. At low pressure the molding cavity in which the injection iscarried out is preferably placed under lower pressure in order to assistthe evacuation of the air. In this case, the method is much less rapid,but it is much simpler then sealing the injection cavity so that themachining tolerances of the mold are greater. This of course translatesinto a lower cost. In addition, the reactive mixtures can then be tintedin the mass.

The invention also relates to a device for using the above-describedmolding method. This device is composed on the one hand by a mold withan internal cavity having the shape of the external peripheral joint, aninjection lip and air holes which are intended for the removal of theair present in the cavity and which are located on the edge of the moldopposite the edge containing the injection lip. The mold only covers theareas of the edges of the multiple glazing so as to enable the means fortraction of the sheets of glass to come closer to the central parts.These traction means are preferably composed of chambers which arecapable of being placed under reduced pressure using a slight vacuum.The mold preferably contains a mixing chamber, located downstream of theinjection lip, which is thin so as to enable manual removal of thepolymerizing plastic in the mixing chamber.

Glazing in accordance with the invention, as shown in FIG. 1a, comprisestwo sheets of glass 1, 1', which are parallel and kept separated by adehydrated air space 2. The sealing and the spacing are provided by twoplastic cords 3 and 4.

The interior cord 3 is composed of an elastomer extruded in the form ofa cord directly onto the glass and is of the rocking type in butylrubber and polyisobutylene as described in French Pat. No. 2,294,313.Due to its composition and its relatively high temperature shortly afterits extrusion, the butyl rubber adheres well to the glass andconstitutes a first sealing barrier. In addition, it contains largequantities of a dehydrating agent, particularly of the molecular sievetype and thus ensures the water-tightness of the interposed air space 2.

After the laying of the interior cord 3 at, for example, 14 mm from theedge of the sheet of glass 1, sheet 1' is put in place. This causes noimmediate deformation of the cord due to the high shock resistance ofthe butyl rubber. As the butyl rubber has a slight tendency to becomedetached from the glass in the presence of liquid water and remainspermanently fairly pliable and sensitive to creepage, it must be coveredand a permanent spacer and a water-tight joint be placed. This triplefunction is provided by peripheral joint 4.

In accordance with the invention, this peripheral joint 4 is composed ofan organic polymer which adheres in a cohesive manner to the butylrubber-based cord during its polymerization. Polyurethane is preferablyused which is a condensation product of a mixture of polyols andpolyisocyanates.

For quality double glazing, it is necessary for the polyurethane to havean instanteous hardness of betwen 50 and 70 Shore A. The instanteoushardness is measured with a hardness meter under DIN 53505 and ISO R868standards; the value indicated corresponds to the highest observeddeviation of the needle of the hardness meter. In addition, its remanentcompression deformation must remain below 25% after a test for 24 hoursat 70° C.

After polymerization, the polyurethane should preferably have an amountof dry material of greater than 97%. In this manner, no chemicaldewpoint appears due to the condensation of the solvents present in thejoint.

In order to assist the formation of strong cohesive bonds between thepolyurethane joint and the butyl rubber-based joint, it is preferable tohave good thermal homogeneity. Since the polyurethane peripheral jointis generally molded directly after the laying of the interior butylrubber-based cord, that is at a time when the butyl cord has atemperature close to 40°-70° C., a polyurethane is preferably selectedwhose optimal temperature of polymerization by reactive injection iswithin that temperature range.

If high pressure is used, a polyurethane is preferably used which has athread time of less than 2 seconds, with the thread time being themoment starting from the initial mixture of polyol-isocyanate basedcompounds from which the degree of reticulation of the polyurethane issuch that its viscosity allows a continuous thread to be drawn.

Tests have been carried out using a formula prepared by B.A.S.F. bearingreference BS RIN 40/165. This formula is a mixture of a compound A(polyols), whose viscosity measured on a Faake® viscosimeter is 1450MPa/sec at 25° C., with its density then being 1.03, and a compound B(isocyanates), in which the percentage of free isocyanate groups is 26.5(% NCO), the viscosity at 25° C. measured on an Epprecht® viscosimeteris 90 MPa/sec and the density is 1.215. The weight ratio of the mixtureA and B is 100 to 28. The reactive mixture, injected under a pressure of200 bars for 1.5 seconds, gives a joint whose physical characteristicsinclude an instanteous hardness of 50 Shore A, breakage constraint at20° C. of 20.4 MPa and stretching to breakage at 20° C. of 450%.

Double glazing, prepared using the above mixture and with a butylrubber-based interposed cord, was placed after 21 days of aging in ahigh humidity oven (55° C.-95% humidity). Reference double glazing, witha polysulfide peripheral joint, was placed under the same conditions. Onthe first day, the two glazings had a same dewpoint at -45° C. Fourteendays later, the dewpoint was -65° C. for the multiple glazing inaccordance with the invention and -54° C. for the glazing with thepolysulfide joint. This decrease in the value of the dewpoints isexplained by the heat activation of the dehydrating agents which thebuty rubber-based cords contain. After 28 days, the dewpoint of theglazing with the polysulfide joint remained unchanged, whereas thedewpoint of the glazing with the joint in molded polyurethane was below-70° C. These values then remained unchanged until the 98th day, whenthe test was stopped. This test shows the very remarkable sealing of theglazing in accordance with the invention, knowing that a glazing with adewpoint below -40° C. is already considered as satisfactory.

In addition, after this cycle of 98 days, it was still impossible toseparate the polyurethane joint from the butyl rubber-based jointwithout destruction of one of the joints.

Substantially identical characteristics are obtained using reactivemixture formulas for reactive injection molding based on aliphaticisocyanates such as those supplied by Recticel, which have the advantageof better ultraviolet resistance than the polyurethane.

If low pressure is used, a polyurethane is preferably selected whosethread time is less than 2 minutes, such as, for example, that sold byRevco under the name Revorin® 20A (Labo I 0021/001 A and I 0021003b).This mixture contains a polyol-based compound A, of the polyether type,whose volume on the pyknometer at 23° C. is 1.05 g/cm³, Brookfieldviscosity is 710 CPS and the dry extract greater than 98% after 3 hoursat 105° C. The second isocyanate-type compound B is called Revorin® 20B(Labo I 0021/003B) with a volume on the pyknometer at 23° C. of 1.12g/cm³ and likewise a dry extract greater than 98%. A mixture in a weightratio A/B =53.8/46.2 has an unmolding time of 1.5 minutes at 23° C.

Such polyurethanes fully guarantee the triple function given to theperipheral joint, but it should be noted that this triple function isnot specific to molded polyurethane-type plastic joints. In effect, thisis provided in prior art glazing by polysulfide-type injected plasticjoints. However, a molded polyurethane-type plastic joint has advantagesboth with regard to the product obtained and with regard to themanufacture of this product.

From the point of view of the final product, a multiple glazing as isshown in FIG. 1a, has remarkable sealing due, on the one hand, to theimpermeability of polyurethane and, on the other hand, to the obstaclesplaced in the path of the water up to the interior cord. In effect, theglass-joint interface constitutes a choice path for infiltrations butwith a molded joint, the thickness of this leak is already reduced dueto the fact that the joint follows perfectly the micro-contours of thesurface of the glass and is pressed thereagainst like a suction cup. Inaddition, if, as shown here, the molded polyurethane joint has wings 5which in part cover the exterior surface of the glazing, the path whichthe water must follow up to the cord is considerably increased such thatthe probability of its succeeding in penetrating is strongly reduced.Such a configuration also enables the interior cord to be masked.

A further advantage comes from the fact that the exterior dimensions ofthe overmolded glazing correspond exactly to the dimensions of the moldand are therefore perfectly defined whereas it is sometimes difficult toperfectly achieve the dimensions of the sheets of glass. It is also veryadvantageous to be able to obtain a single exterior dimension of theglazing for a whole range of thicknesses of air spaces and sheets ofglass. This, for example, allows a choice between various types of heator even sound insulation to be offered on the basis of a single frame.

It should be noted that the edges of the multiple glazing which are moreespecially fragile and injurious, are thus protected, which facilitatesstocking, handling and laying of the glazing which can even withstandshocks.

FIG. 1b shows a double glazing compound of two sheets of glass 11, 11'separated by a dehydrated air space 12 or possibly by any other gasselected for its insulating property. This interposed space 12 isdefined by rigid profiles 13, comprising for example aluminum. Theseprofiles contain large quantities of a dehydrating agent 14, for examplein the form of molecular sieve bearings and in contact with theinterposed air space through slit 15. Sealing between the sheets ofglass and the profiles is obtained by the deposit of a fine interposedcord 16 formed of a polyisobutylene and/or butyl rubber-based mastic. Itis therefore possible to use a polymerizing reactive mixture to providejoint 17. Such glazing is of comparable quality to the preceding onefrom the point of view of sealing and life span. Its cost is greaterbut, on the other hand, it is well suited for custom work, such as arenovation for example.

It is within such a framework that glazing of the type shown in FIG. 1cis more especially used. This glazing contains various elements (21,21', 22, 23, 24, 25, 26 and 27) corresponding to the elements (11, 11',12, 13, 14, 15, 16 and 17) of the glazings of the preceding type, butwhich are more especially characterized by a projection 28 of the moldedjoint 27, which projection is more especially intended for mounting inold grooves intended solely to receive single glazing. A singleprojection has been shown, but it is possible to provide several in anydesired shape.

It should be noted that nothing prevents such projections with a glazingof the type shown in FIG. 1a or any other projections enabling, forexample, mounting of the glazing in dry grooves.

The combination of the covering wings 5 and the use of the peripheraljoint and the projections of any type 28 enable multiple glazing to beobtained wherein that which we will call the peripheral mounting part,i.e., the useful mounting zone intended to be placed in a groove andheld in place therein, is of a size which is perfectly independent fromthe thickness of the bay itself, that is of the thickness of the airspace and the sheets of glass.

In addition, mounting of the bay, whether for renovation or even newconstruction, can be by a careful very simplified placement of theprojections 28; the glazing can then be directly nailed or screwed onthe frame.

A further particularly original characteristic of the multiple glazingin accordance with the invention comes from its method of manufacture,which is described by reference to FIGS. 2 and 3.

After having been assembled, the assembly formed of two sheets of glassand the interior butyl rubber and/or polyisobutylene-based cord isplaced in a mold, a diagram of the principle of which is given viewedfrom above (FIG. 2) and in cross-section (FIG. 3).

The mold used contains a lower component 31 and an upper component 32which is capable of being removed to enable the introduction and theremoval of the multiple glazing. Each half-mold contains a foot 33 (34respectively) on which the glass sheet 35 (36 respectively) is supportedand which defines over the entire periphery of the glazing a groove 37into which the reactive mixture is injected. Since the two sheets ofglass are at least partially separated by a butyl rubber and/orpolyisobutylene-based cord 38, the sealing between the glass and themold at the feed 33 and 34 cannot be obtained by compression withoutcrushing cord 38. To overcome this, a low pressure chamber 39 isprovided by means of channels 40, 41 in which a slight vacuum is appliedwhich is created for example by means of a vacuum pump, not shown here,which maintains the glass up against the feet 33, 34.

It should be noted that the channels 40, 41 also allow the introductionof the air under pressure at the end of the molding operation so as tofacilitate the detaching and removal of the finished glazing.

In accordance with a particularly important characteristic of theinvention, the vacuum created in the low pressure chamber 39 can be usedto modify or adjust the thickness of the interposed butyl rubber-basedcord so as to render it perfectly functional with a nominal thickness.In effect, if the vacuum is used to separate the sheets of glass, areduction in the thickness of the cord is obtained without anymodification in its surface in contact with the glass and thereforewithout any consequence in the degree of sealing provided by the joint.This property can possibly be used for the manufacture of double glazingwith air spaces on the order of 2 cm for example. It also overcomesproblems likely to be caused by a possible creeping of the interiorcord.

Conversely, the cord can be compresed at the moment of closure of themold. Therefore, it is useless to press the sheets of glass against thebutyl rubber-based cord upon constitution of the provisional multipleglazing, the pressing being preferably carried out at the moment ofclosing the mold.

Each half-mold 33, 34 is provided with uniform heating means; half-moldsprovided with circulation of a heat-bearing fluid, such as oil, arepreferably used.

The injection is carried out through the injection lip 42 located on oneof the sides of the mold, between the two half-molds 31 and 32. This lipis preferably extremely fine and consequently grossly schematized on thedrawing for greater clarity. Above the injection lip 42 is a mixingchamber which is of the type commonly known as a "carp tail". Thischamber is supplied by a static mixer and an injection pump. Thesevarious components are well known in the art and are not shown here.

The air present in the cavity defined by the two half-molds 31, 32escapes through vents 43 placed on the side of the mold opposite theinjection edge. These vents 43 are preferably at a higher level thanthat of the injection lip 42. For this, the mold is inclined at an angleof a few degrees in relation to the horizontal, even up to 30°, with theinjection edge then being at the bottom.

The mold which has just been described is more particularly suitable forhigh pressure injection of the reactive mixture, with a so-called RIMmachine, such as that offered by Krauss Kaffei, which provides a perfectmixture of the reagents and requires no rinsing or cleaning of themixing chamber and with which any obstruction of the mixing head by thereactive mixture is impossible, even with prolonged production times.

The exterior surface of the glass destined to be covered by thepolyurethane molded joint can be treated with a primer or an adhesionpromoter, for example with a solution of 1% saline in ethanol. The useof such a primer is not necessary and moreover only the exterior surfaceof the glass, which is very easily accessible, can receive thistreatment, such that the priming poses no particular difficulty.

An unmolding agent, for example of the Acmos Fluoricon® 35-20 type,which is a mixture of wax and white spirit, is preferably pulverizedonto the walls of the mold. This unmolding agent can also be apolyurethane paint, which thus enables a glazing to be provided with acolored joint, for example white, since the joint is naturally black.

When the injection of the reactive mixture is carried out under apressure below 10 bars, preferably between 3 and 7 bars, a mold ispreferably used whose injection zone is schematized in FIG. 4. This moldcan moreover also be used for high pressure injection with thelimitations specified in the following description.

The lower 44 and upper 45 molds are heat-insulating due to an interiorcircuit 45 which is traversed by a heat-insulating liquid--water oroil--at for example 60° C. As above, they are provided with reducedpressure chambers 47, 48 which act, by means of channels 49, on theglass sheets 50, 51 of the insulating glazing which, at this stage,contains only a peripheral butyl rubber joint 52. For a softer contactwith the glass, the channels 49 traverse rubber pads 53. To prevent thesheet of glass from slipping at the moment of or after the closure ofthe mold, incompressible molded plastic blocks 54, 54' are providedwhich are made for example of a polyurethane with suitable hardness.These blocks 54, 54' are laid in housings 55, 56 in the half-molds.These housings 55, 56 are, as shown here, of a size greater than thesize of the blocks 54, 54'. Consequently, even under the pressure of thesheets of glass, blocks 54, 54' always occupy the same volume and do notcontribute to sealing the cavity 57 in which the reactive mixture isinjected through injector 58. Blocks 54, 54' are fixed by means of lugs59, 60.

Cavity 57 is defined here by the walls 61 of the lower mold 44, and 62of the upper mold 45 and by a spacer 63 containing a boss which ishoused in a cavity 64 of the lower mold. Such a spacer 63 is onlysuitable for injection pressures of the reactive mixture, pressures forwhich sealing can be obtained simply by acting on the compressability ofthe plastic spacer 63.

For high pressure injections, a lower half mold is used which abuts onthe upper half-mold. This, however, no longer enables the same mold tobe used for glazings of the same size, but whose thicknesses vary. Thisspacer 63, which is for example made of aluminum, further enables theexterior geometrical shape of the molded joint to be varied as afunction, for example the window for which the glazing is intended.Thus, studs 63' are provided in this case to define holes along theprojection produced with the shape of the mold shown here.

The sealing of the glazing is preferably carried out on an edge 65,whose width is, for example equal to 5/10 mm, which projects slightly inrelation to blocks 54, 54', and on which the sheet of glass is platedwhen chambers 47 and 48 are placed under reduced pressure. Due to theinevitable small imperfections of the surface of the glass and of themachining of the mold, the sealing line can in effect, in extreme cases,move on all the points of the edge 65. In order to have a perfectlyclean joint edge, it is therefore preferable for the edge to be as fineas possible.

Such a mold can be produced in any easily machinable material such assteel, aluminum or even wood or plexiglass. It is preferably providedwith a teflon coating which removes the need to use a unmolding agent ifa colored joint is desired, since the polyurethanes condense inapproximately 90 seconds and are capable of being tinted.

Finally, with regard to the mold, it should be noted that the reducedpressure can be advantageously maintained on a single surface of theglazing during opening of the mold, then be stopped and replaced with aslight overpressure which assists in the removal of the glazing.

In order to use the method of injection in accordance with theinvention, particular care should be taken that the two components arethoroughly mixed in the desired proportions, while keeping a high rateof supply which is compatible with high volume production.

If injection pressures of close to 200 bars are used, we have alreadyindicated that a rising head such as that developed for the RIM methodis satisfactory.

For injection pressures lower than 10 bars, a material circuit such asthat schematized in FIG. 5 is more particularly preferred.

Upstream, this circuit contains 66, 67 and 68 in which components A andB and a solvent S for the two components, such as, for example, benzenefor polyurethane, are respectively stocked. These containers 66, 67 areclosed by means of sealed covers 69, 70 and 71. In addition, forproducts sensitive to oxygenation or hydration, a slight nitrogen ordehydrated air overpressure is provided. This pressurization can alsoassist in the filling of circuits 72, 73, 74. This filling can also becarried out by means of pumps which are adapted to the components, suchas pumps with bearings 75, 76, 77.

Two dosing chambers for volumetric dosing, each grouped in pairs, areassociated with each container for components A and B. Circuit 72 forcompound A therefore extends at 78 to the dosing chamber 79 and at 80 tothe dosing chamber 81. Likewise, circuit 78 for compound B fills chamber83 by means of channel 82, and chamber 85 by means of channel 84.

Each chamber is closed by means of a floating piston 86, 87, 88, 89, thestem of which, when remounting, comes against a path end 90, 91, 92, 93.The occultation of each path end 90, 91, 92, 93 sets off the closing ofan associated electrovalve 94, 95, 96, 97. Each dosing chamber is thusfilled independently of the others. The level of the path ends 90, 91,92, 93 can of course be adjusted to modify the mixture ratios ofcompound A/compound B.

The order for closing the electrovalves (94, 95) (96, 97), respectively,of a same pair of dosing chambers controls the thrust of the associatedjack 98, 99, respectively, which pushes the products out of the chambersthrough anti-return valves located at the bottom thereof. Product A thusrejoins pipe 102 through pipes 100 or 101, while product B rejoins pipe103 by passing through pipes 104 or 105. These pipes 102 and 103 areclosed by valves 105 and 106 which direct the products either towardsthe junction block 107 (injection in progress) or by pipes 108 and 109towards the reserve volumes 66 and 67, for closed circuit operation. Ifthe injection is in progress, compounds A and B pass through a firststatic mixer 110 and are taken up by the injection pump 111 whichdelivers the mixture through a second static mixer 112 and then throughpipe 113 to the mold.

Turning for a moment to closed circuit operation, it should be pointedout that the junction block 107 is then supplied with solvent throughpipe 74 after opening of the valve 114. The static mixers 110, 112 andthe pump 111 are thus cleaned and the solvent is sent back through pipe115 to the container 68 after passage on a decanting sieve.

Such a material circuit is both very sure and very rapid since thelength of the pipes is very small, which guarantees arrive of thecompounds under the best conditions.

Finally, FIG. 6 illustrates a static mixer adapted for good working ofthe invention, which contains 3 series 116, 117, 118 of 3 coaxialchambers 120. These chambers communicate through small diameter pipes119. The mixture of the components is thus released into each chamber120 and then calendered into pipes 119. It should be noted that the axisposition of the chambers removes any preferential path for the mixture.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. A multiple glazing, comprising:at least twosheets of glass separated by an interposed gas space; means formaintaining said glass sheets mutually substantially parallel, whereinsaid means for maintaining comprises a cross-braced frame, said framecomprising a rigid metal profile having a glass contact surface andcovered on said glass contact surface with a butyl rubber orisobutylene-based joint, and a peripheral joint and wherein saidperipheral joint comprises a plastic adhering in a cohesive manner tosaid cross-braced frame.
 2. The multiple glazing of claim 1, whereinperipheral joint comprises a plastic obtained by in situ condensation ofthe mixture of at least two liquid reagents.
 3. The multiple glazing ofclaim 1, wherein said peripheral joint extends to cover the entireperipheral part of the external surface of said glazing.
 4. The multipleglazing of claim 1, wherein said peripheral joint contains at least onemounting projection.
 5. The multiple glazing of claim 4, wherein theshape and dimensions of said mounting projection are independent of thethickness of said gas space and the thickness of said glass sheets. 6.The multiple glazing of claim 1, wherein said plastic of said peripheraljoint is polyurethane obtained by injection and in situ polymerization.7. The multiple glazing of Claim 6, wherein said polyurethane has athread time of less than 2 minutes.
 8. The multiple glazing of Claim 7,wherein said thread time is less than 2 seconds.
 9. The multiple glazingof Claim 6, wherein after condensation, said polyurethane has aninstanteous hardness of between 50-70 Shore A, an extension to breakageof 400% at 20° C. and a remanent deformation to compression lower than25% after a test for 24 hours at 70° C.
 10. A multiple glazing,comprising:at least two sheets of glass separated by an interposed gasspace; means for maintaining said glass sheets mutually substantiallyparallel, wherein said means for maintaining comprises the cross-bracedframe, said frame comprising a member selected from the group consistingof a butyl rubber cord and a polyisobutylene-based cord, and aperipheral joint, and wherein said peripheral joint comprises a plasticadhering in a cohesive manner to said cross-braced frame.
 11. Themultiple glazing of claim 10, wherein said peripheral joint comprises aplastic obtained by in situ condensation of a mixture of at least twoliquid reagents.
 12. The multiple glazing of claim 10, wherein saidplastic of said peripheral joint is polyurethane obtained by injectionand in situ polymerization.
 13. The multiple glazing of claim 10,wherein said polyurethane has a thread time of less than 2 minutes. 14.The multiple glazing of claim 13, wherein said thread time is less than2 seconds.
 15. The multiple glazing of claim 12, wherein aftercondensation, said polyurethane has an instantaneous hardness of between50-70 Shore A, an extension to breakage of 400% at 20° C. and a remanentdeformation to compression lower than 25% after a test for 24 hours at70° C.
 16. The multiple glazing of claim 10, wherein said perhipheraljoint extends to cover to the entire peripheral part of the externalsurface of said glazing.
 17. The multiple glazing of claim 10, whereinsaid peripheral joint contains at least one mounting projection.
 18. Themultiple glazing of claim 17, wherein the shape and dimensions of saidmounting projection are independent of the thickness of said gas spaceand the thickness of said glass sheets.